Spark arresting incinerator

ABSTRACT

A spark arresting incinerator apparatus for burning combustible solid materials without the release of hot embers or ash capable of igniting materials outside the incinerator includes a firebox to contain the combustion, a grate disposed across the bottom of the firebox to support materials to be burned, an ash box disposed below the firebox and grate and connected to the firebox, the ash box having at least one screened and shielded combustion air inlet, a generally pyramidal cupola disposed above and connected to the firebox, and a chimney disposed above and connected to the cupola for the exit of combustion gases from the incinerator. The chimney includes a plurality of baffle plates each extending partially across the interior of the chimney, with the baffle plates disposed in staggered offset relation to each other, and also preferably includes a spark arrestor connected to the top of the chimney.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. Provisional PatentApplication Ser. No. 60/809,091, filed May 30, 2006, by the sameapplicant.

FIELD OF THE INVENTION

The present invention generally relates to incinerators, and in itspreferred embodiments more specifically relates to an incineratorstructure that protects against the release of sparks or embers from theincinerator.

BACKGROUND OF THE INVENTION

Residents of rural areas often do not have access to garbage and trashdisposal services or to landfills for disposal of their householdgarbage and trash. It is very common, therefore, for such residents toburn their household trash. During periods of drought or other periodswhen the surrounding vegetation is dry, fugitive sparks and embers fromthe burning of trash can pose a heightened risk of igniting surroundingvegetation. It is common for governmental authorities to imposerestrictions on burning during such periods as a safety measure.Although burning restrictions are effective in limiting fires, they docreate hardships for rural residents because of the accumulation oftrash. Accumulated trash is not only visually unsightly but can alsocreate health hazards and attract pests that can, themselves, createhealth hazards.

Conventional incinerators cannot be safely used to burn trash and thelike during periods of high fire risk, because conventional incineratorsare not sufficiently effective in preventing the release of embers andother solid combustion products that are the primary cause of accidentalfires. The entrainment of embers and the like in the combustion gasesthat flow from a conventional incinerator through a chimney atrelatively high velocity pose the primary risk, and conventional sparkarrestors disposed at the chimney outlet are not sufficiently effectiveto eliminate that risk.

The problems with accumulated trash can prompt some rural residents todispose of trash improperly and illegally, such as by dumping trashand/or garbage along roadsides and/or on unoccupied land. Residents mayalso ignore an imposed burning ban and burn trash anyway, exacerbatingthe fire risk.

There is a need for an efficient, effective, and affordable incineratorapparatus that can be utilized to incinerate household generated trashand garbage without allowing the escape of embers and ash capable ofigniting combustible materials outside the incinerator.

SUMMARY OF THE INVENTION

The present invention provides an incinerator apparatus designed for useat rural households and small business operations for the safe burningof trash and other combustible materials. It is an object of theinvention to contain and control the combustion of such materials withinthe incinerator. It is also an object of the invention to prevent theemission of sparks or embers that could ignite vegetation or othercombustible materials outside the incinerator. It is still further anobject of the invention to provide an incinerator that is appropriatelysized for use by a single household, and that may be effectively andsafely operated by a single person. It is still another object of theinvention to provide an incinerator that is relatively inexpensive andaffordable to those who have a need for such an apparatus.

The structure and features of the incinerator apparatus of the inventionwill be described below, with reference to the accompanying drawingfigures.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front elevation view of the preferred embodiment of theincinerator apparatus of the invention.

FIG. 2 is a sectioned side elevation view of the chimney of a firstembodiment of the incinerator apparatus, with the baffles in a firstorientation.

FIG. 3 is a sectioned side elevation view of the chimney of anembodiment of the incinerator apparatus, with the baffle plates in asecond orientation.

FIG. 4 is a top plan view of a square chimney embodiment, with baffleplates.

FIG. 5 is a side elevation view of the preferred embodiment of theincinerator apparatus of the invention, with steps extending to thefront of the apparatus.

FIG. 6 is a side elevation view of an embodiment of the incineratorapparatus of the invention, without access steps.

DESCRIPTION OF THE INVENTION

The incinerator apparatus of the invention, generally designated byreference number 10, comprises as principal components or sections afirebox 11, an ash box 12 disposed below the firebox, a loading cupola13 disposed above the firebox, a chimney 14 above the cupola, and asupport base 15.

In the preferred embodiment firebox 11 is configured as a hollow,generally cubical box with an open top and an open bottom, having afront wall 16, a rear wall 17, side walls 18 and 19, an upper edge 20and a lower edge 21. It is preferred that the height of firebox 11,between upper edge 20 and lower edge 21, but approximately equal to oreven greater than the width of the side and rear walls. A grate 22 isdisposed across the bottom of the firebox at lower edge 21, between thefirebox and the ash box for supporting material loaded into the fireboxfor combustion and to allow ash to fall from the firebox into the ashbox. In the preferred embodiment the upper portion of front wall 16extends solidly across the upper portion of the firebox between sidewalls 18 and 19, and the lower portion of the front wall 16 of thefirebox is formed by doors 23 and 24, each pivotally connected to one ofside walls 18 and 19, respectively. Doors 23 and 24 are releasablysecured in a closed position by firebox latch 25. Access to the interiorof firebox 11 through doors 23 and 24 is provided for cleaning, and forpre-combustion loading of material to be incinerated into the firebox.When the incinerator apparatus is in operation doors 23 and 24 shouldremain closed, both for the safety of the operator and to prevent theescape of hot combustion products.

Ash box 12 includes side walls 26 and 27, a rear wall 28, and a closedbottom 29. Ash box 12 also has an upper edge 30 surrounding an open top.The majority of the front of the ash box is closed by doors 31 and 32,each of which is pivotally connected to one of side walls 26 and 27.Doors 31 and 32 are provided for the removal of ash from the ash box,and are releasably secured in a closed position by ash box latch 33. Theportion of the front of the ash box between the upper edge of doors 31and 32 is open to provide a front combustion air inlet 34, covered byscreen 35 to provide an inlet for combustion air. Side walls 26 and 27and rear wall 28 also preferably include combustion air inlets 34adjacent to their upper edges, also covered by screens 35. The depth ofash box 12 is sufficient to accommodate at least the quantity of ashthat is reasonably anticipated to accumulate during incineration of abatch of material, without interfering with the flow of combustion airthrough the air inlets in the ash box. During operation of theincinerator a draft through the structure is created by the outflow ofhot combustion product gases, sufficient to pull air into the structurethrough the combustion air inlets while preventing the outflow ofcombustion products from those air inlets. The combustion air inlets aredisposed at the upper edge of the ash box so that any embers or otherhot solids that fall through grate 22 fall past the air inlets, andscreens 35 are provided to assure that no embers or other hot solidparticles are allowed to escape through the air inlets.

Ash box 12 and firebox 11 may be formed as an integral unit, with sidewalls 26 and 27 of the ash box formed as extensions of side walls 18 and19 of the firebox, and with rear wall 28 of the ash box formed as anextension of rear wall 17 of the firebox. Alternatively, the firebox andthe ash box may be separately formed and connected during constructionof the incinerator apparatus.

In the preferred embodiment, cupola 13 is configured as a truncatedpyramid, with a front wall 36, side walls 37 and 38, and a rear wall 39.The base, at the lower edge 40 of the cupola, and the top, at the upperedge 41 of the of the cupola, are open, to form open passageways fromthe firebox to the cupola and from the cupola to chimney 14,respectively. It is preferred that the height of cupola 13, between thebase and the top, be generally equal to or greater than the width of thebase along the lower edge of each of the walls. The lower edge of cupola13 is configured to mate with the upper edge of firebox 11, and thecross-sectional dimensions of the cupola narrow toward its top. Aloading door 42 is provided in front wall 36 to close an opening 43 inthe front wall for introduction of material to be burned either prior toinitiation of combustion or during incineration if needed. Door 42 ispreferably pivotally connected to front wall 36 at the upper edge of thedoor, so that door 42 can be lifted upward using handle 44 and willautomatically close when released. In this embodiment a latch to securedoor 42 in a closed position is not necessary, although a latch couldreadily be provided if desired.

Chimney 14 preferably comprises a hollow body with a continuous sidewall 45, an open lower end 46 and an open upper end 47. Chimney 14 isdisposed over and extends upwardly from cupola 14, and is connected atlower end 46 to the top 41 of the cupola so as to prevent the escape ofcombustion products through the connection between the chimney and thecupola. In the preferred embodiment the cross-sectional configuration ofchimney 14 is square, partly to simplify the construction andinstallation of baffles, but the scope of the invention is not limitedto any particular configuration, and other configurations, such ascircular, could readily be used if desired.

When combustible materials are burned, hot combustion products,primarily gases but with solids entrained in the gases as smoke, ash,and embers, rise from the combustion zone, and in most combustionapparatus the combustion products are routed through a chimney with asubstantially reduced cross-sectional area in comparison to the area ofthe combustion zone. As a result of the reduction in area of thechimney, the velocity of the combustion products flowing upwardlythrough the chimney increases, which conventionally serves to assure theexhaust of combustion products from the combustion zone and to reducethe pressure within the combustion zone to assure the inflow ofcombustion air.

The movement of combustion products through a chimney at a relativelyhigh velocity has a tendency to entrain embers and other relativelylarge particles in the gas flow, which particles are frequently releasedfrom the chimney with the combustion gases. Embers drop out of the flowof combustion gases soon after they exit from the chimney, and suchfugitive embers are the primary cause of accidental fires outside thecombustion apparatus.

In the preferred embodiment of the incinerator apparatus of theinvention, the combined height of firebox 11 and cupola 13 above grate22 is relatively high in proportion to the horizontal dimensions ofthose components, and chimney 14 is relatively short in comparison tothe chimney of a conventional incinerator, fireplace, or otherconventional combustion apparatus. Further, the cross-sectional area offirebox 11 at top 20 is essentially the same as the cross-sectional areaat grate 22, and the cross-sectional area of cupola 13 reduces graduallybetween the connection of cupola 13 to firebox 11 and the connection ofchimney 14 to the cupola. As a result of this structure, combustiongases move upward through firebox 11 and cupola 13 a relatively lowvelocity and with an increased retention time, and move through chimney14 at relatively low velocity. Because of the low velocity of the flowof combustion gases, embers and other solids are much more likely todrop out of the combustion gases within the firebox or cupola, beforeentering the chimney, and the entrainment of embers and other solids inthe combustion gases that flow through the chimney is greatly reduced.

In addition, as combustion gases move upward through the reducingcross-sectional area of cupola 13 toward the entry into chimney 14, theflow of the combustion gases is not laminar, but becomes more turbulent,with the creation of swirls and eddies within the cupola. Generally, theflow pattern is such that the velocity of the flow at the cupola wallsis lower than the velocity of the gas flow closer to the center of thecupola. Embers and other solids entrained in the combustion gases areforced toward the walls of the cupola, into the area of reducedvelocity, where they are more likely to drop out of the gas flow andreturn to the firebox.

As further protection against the escape of embers from the chimney,chimney 14 preferably includes a plurality of baffle plates 48 disposedin the interior of the chimney, in the flow path of the combustion gasesand any remaining solids through the chimney. Baffle plates 48preferably comprise thin flat plates, each connected at one end to theinterior of sidewall 45 of the chimney and extending across the interiorof the chimney through more than half the interior of the chimney. Thebaffles are disposed and connected in a staggered, alternatingrelationship to create a sinuous path through the interior of thechimney. Combustion gases and any entrained ash or embers entering thechimney come into contact with the first baffle encountered in the flowpath, forcing the gases, etc., to move laterally past the free end ofthe baffle to continue moving up the chimney to the next baffle, and soon through the chimney. Pieces of ash and/or embers with sufficient massto retain enough heat to pose an ignition threat outside the chimneywill not remain entrained in the smoke flow through the chimney aroundthe baffles to its upper end 47, but will drop out of the smoke flowbefore exiting the chimney. Although, as noted above, chimney 14 may beformed with any desired cross-sectional configuration, a squareconfiguration is preferred not only to facilitate the fabrication andinstallation of baffle plates 48, but also because a squareconfiguration increases the turbulence of the flow of combustion gasesthrough the chimney. Embers and other solids are less likely to remainentrained in a turbulent flow, partly because of increased retentiontime within the chimney, and less likely to escape from the incineratorapparatus to pose a fire risk.

The scope of the invention encompasses a number of variations in theconstruction and placement of baffle plates 48. As one example, thebaffles may be disposed with the plane of each baffle perpendicular tothe longitudinal axis of the chimney, or may be inclined downward at anangle to the chimney axis. An upward incline could be used but is Potpreferred because of increased risk of passage of embers past thebaffles. In the preferred embodiment baffle plates 48 are formed assolid plates, but in an alternative embodiment the baffles may be formedof a screen or mesh material in a supporting frame, to allow smoke andother gaseous combustion products to pass directly through the baffleswhile preventing the passage of ash or embers that would pose anignition risk.

In the preferred embodiment of the incinerator apparatus a screenedspark arrester 49 is disposed at the upper end 47 of chimney 14, tofurther assure that no hot ash or embers posing an ignition risk escapethe chimney. Spark arrester 49 may be of any conventional design.Although not contemplated to be necessary, a spark arresting screen orgrate may also be disposed at lower end 46 of chimney 14, to trap anylarge particles remaining in the flow of combustion gases at that pointand prevent their entry into the chimney.

As further protection against the escape of ash or embers from ash box12 carried by cross winds blowing through the combustion air inlets,wind shields 50 may be connected to the ash box above each air inlet toextend outwardly and downwardly at an angle, as shown in FIG. 4, toshield against cross winds without interfering with the entry ofcombustion air below the shields. Shields 50 are formed as flatrectangular plates of sufficient length to span across the associatedcombustion air inlet, connected at one edge to the ash box between theair inlet and the upper edge of the ash box, and extending outwardly anddownwardly at a preferred angle of about forty-five degrees, with theopposite edge of the shield disposed below the lower edge of theassociated combustion air inlet. Each shield occludes the associatedcombustion air inlet so as to prevent laterally blowing wind frombypassing the shield and blowing into the ash box through the combustionair inlet, without preventing air from being drawn through the air inletaround the shield.

Support base 15 includes legs 51 extending downwardly from a frame 52that is disposed at the lower edge of ash box 12 to support theincinerator structure above the ground or other surface upon which it isplaced an operated. A set of preferably folding, drop-down steps 53 isalso provided below ash box 12, pivotally connected to frame 52, tofacilitate access to cupola door 42. Steps 53 may also be provided as apermanently deployed non-folding structure that remains in place, or thesteps may be omitted from smaller models of the incinerator, if notneeded for access to the cupola door.

In the preferred embodiment described above the cross-sectionalconfiguration of the principal components of the incinerator apparatusis generally rectangular. However, a rectangular configuration is notessential, and it is to be understood that the scope of the inventionencompasses other configurations as alternative embodiments. As anon-limiting example, ash box 12, firebox 11, and cupola 13 may beformed with a cylindrical configuration. In such an alternativeembodiment the cross-sectional configuration of chimney 14 may becylindrical, or the rectangular configuration of the preferredembodiment may be retained to, as noted above, facilitate the connectionof baffle plates 48.

The foregoing description of the apparatus of the invention is intendedto be illustrative and not limiting. In addition to the embodiments andvariations described above, the apparatus is susceptible to furthervariations, all within the scope of the invention, in accordance withthe following claims.

1. A spark arresting incinerator apparatus for burning solid combustiblematerials, comprising, a firebox formed as a hollow enclosure with asurrounding sidewall, an upper edge, a lower edge, an open top and anopen bottom, said firebox having a height and a width, with said heightbeing approximately equal to said width; a grate for supporting thecombustible materials to be burned, said grate connected across saidopen bottom of said firebox at said lower edge thereof, said gratehaving openings therein for the passage of combustion air therethroughand for the passage of ash therethrough; an ash box formed as a hollowenclosure with a surrounding side wall, an upper edge, a lower edge, anopen top, and a closed bottom at said lower edge, said ash box disposedbelow said firebox adjacent to said grate with said grate extendingacross said open top of said ash box at said upper edge thereof; acupola formed as a truncated hollow pyramid with a surrounding sidewall,an upper edge, a lower edge, an open top and an open bottom, said cupolaconnected at said lower edge bottom to said upper edge of said fireboxso as to form an open passageway from said firebox to said cupola; and achimney formed as a hollow enclosure with an open interior and asurrounding sidewall, an open upper end and an open lower end, saidchimney connected at said lower end to said upper edge of said cupola soas to form an open passageway from said cupola to said chimney, saidchimney including a plurality of baffle plates each connected to saidsidewall of said chimney and extending partially across said openinterior of said chimney, said baffle plates disposed in separatedrelation in said open interior of said chimney between said upper endand said lower end in staggered, offset relation to each other.
 2. Thespark arresting incinerator of claim 1, wherein said ash box furtherincludes a screened combustion air inlet penetrating said sidewall atsaid upper edge of said ash box.
 3. The spark arresting incinerator ofclaim 2, wherein said ash box further includes a shield plate connectedto said sidewall of said ash box between said combustion air inlet andsaid upper edge of said ash box, said shield plate extending downwardlyand outwardly at an angle over said combustion air inlet so as toprevent wind from blowing directly through said combustion air inletwithout closing said combustion air inlet.
 4. The spark arrestingincinerator of claim 1, wherein said cupola further includes a loadingopening in said sidewall, for loading materials to be burned, and a doorpivotally connected to said sidewall for closing said loading opening.5. The spark arresting incinerator of claim 1, wherein said fireboxincludes a door formed in said sidewall of said firebox.
 6. The sparkarresting incinerator of claim 1, wherein said ash box includes a doorformed in said sidewall of said ash box.
 7. The spark arrestingincinerator of claim 1, wherein said chimney is square incross-sectional configuration, and wherein each of said baffle plates isrectangular.
 8. The spark arresting incinerator of claim 1, wherein saidchimney has a longitudinal axis, and wherein said baffle plates aredisposed perpendicular to said longitudinal axis.
 9. The spark arrestingincinerator of claim 1, wherein said chimney has a longitudinal axis,and wherein said baffle plates are disposed at a downward angle relativeto said longitudinal axis, such that said baffle plates are inclinedtoward said lower end of said chimney.
 10. The spark arrestingincinerator of claim 1, further comprising a support base having asupport frame disposed at said lower edge of said ash box, and aplurality of legs extending downwardly from said support frame.
 11. Aspark arresting incinerator apparatus for safely burning solidcombustible materials and preventing the release of hot embers or ashfrom the apparatus, comprising, a firebox formed as a hollow enclosurewith a surrounding sidewall, an upper edge, a lower edge, an open topand an open bottom, and a latchable door for providing access to saidfirebox for the exterior thereof; a grate for supporting the combustiblematerials to be burned, said grate connected across said open bottom ofsaid firebox at said lower edge thereof, said grate having openingstherein for the passage of combustion air therethrough and for thepassage of ash therethrough; an ash box formed as a hollow enclosurewith a surrounding side wall, an upper edge, a lower edge, an open top,and a closed bottom at said lower edge, said ash box disposed below saidfirebox adjacent to said grate with said grate extending across saidopen top of said ash box at said upper edge thereof, said ash box havinga latchable door for access to said ash box for the purpose of removingcooled ash therefrom, and said ash box having a screened combustion airinlet penetrating said sidewall adjacent to said upper edge for theentry of combustion air below said grate; a cupola formed as a truncatedhollow pyramid with a surrounding sidewall, an upper edge, a lower edge,an open top and an open bottom, said cupola connected at said lower edgebottom to said upper edge of said firebox so as to form an openpassageway from said firebox to said cupola, said cupola having aloading door in said sidewall for the introduction of combustiblematerials to said firebox through said open bottom of said cupola; and achimney formed as a hollow enclosure with an open interior and asurrounding sidewall, an open upper end and an open lower end, saidchimney connected at said lower end to said upper edge of said cupola soas to form an open passageway from said cupola to said chimney, saidchimney including a plurality of baffle plates each connected to saidsidewall of said chimney and extending partially across said openinterior of said chimney, said baffle plates disposed in separatedrelation in said open interior of said chimney between said upper endand said lower end in staggered, offset relation to each other, and saidchimney further including a spark arrestor connected to said upper endof said chimney.
 12. The spark arresting incinerator of claim 11,further comprising a support base having a support frame disposed atsaid lower edge of said ash box, and a plurality of legs extendingdownwardly from said support frame.
 13. The spark arresting incineratorof claim 12, further comprising a set of steps connected to said supportbase and extending downwardly and outwardly therefrom.
 14. The sparkarresting incinerator of claim 13, wherein said steps are pivotallyconnected to said support base such that said steps are movable betweena first position against said support frame and a second positionextending downwardly and outwardly from said support frame.
 15. Thespark arresting incinerator of claim 11, wherein said ash box furtherincludes a shield plate connected to said sidewall of said ash boxbetween said combustion air inlet and said upper edge of said ash box,said shield plate extending downwardly and outwardly at an angle oversaid combustion air inlet so as to prevent wind from blowing directlythrough said combustion air inlet without closing said combustion airinlet.
 16. The spark arresting incinerator of claim 11, wherein saidfirebox is of generally cubical configuration, and wherein thecross-sectional configurations of said ash box, said cupola, and saidchimney are generally rectangular.
 17. The spark arresting incineratorof claim 11, wherein said chimney has a longitudinal axis, and whereinsaid baffle plates are disposed perpendicular to said longitudinal axis.18. The spark arresting incinerator of claim 11, wherein said chimneyhas a longitudinal axis, and wherein said baffle plates are disposed ata downward angle relative to said longitudinal axis, such that saidbaffle plates are inclined toward said lower end of said chimney.
 19. Aspark arresting chimney for conveying combustion gases from a combustionapparatus while preventing the passage of burning embers through thechimney, comprising, a hollow body with an open interior and asurrounding sidewall, an open upper end and an open lower end; and aplurality of baffle plates each connected to said sidewall and extendingpartially across said open interior, said baffle plates disposed inseparated relation from each other in said open interior of said chimneybetween said upper end and said lower end in staggered, offset relationto each other.
 20. The spark arresting chimney of claim 19, wherein saidbody has a longitudinal axis, and wherein said baffle plates aredisposed perpendicular to said longitudinal axis.
 21. The sparkarresting chimney of claim 19, wherein said body has a longitudinalaxis, and wherein said baffle plates are disposed at a downward anglerelative to said longitudinal axis, such that said baffle plates areinclined toward said lower end of said body.